Found it on another Teardown-site: It’s a 36 channel LED driver with I2C connection with the name “IS31FL3236”. Although the datasheet is dated from Sepember 2016 the chip already seems to be on “NRND” state (not recommended for new designs)… Strange.

Thanks for the Video! Could you post, which LED driver has been used in the Echo Dot 2nd Gen? Thanks a lot!

Hi, if still interested in this: I’ll generate a schematic out of the microphone/LED-PCB in the next weeks, because I want to make it smaller and add some sensors as well. Mail me to “kueder (at) gmx . ch”.

Did you see the MID traces on the housing here? I think they're there to improve the GND counterpart to the antenna by capacitivly coupling to the ear! Great idea, isn't it?

TPS743 IMHO doesn't exist. Think it's a simple TPS7430 or TPS74301 LDO from TI.

Is there someone who understood the working of the antenna? Well, it's attached DIRECTLY on the battery. Normally this won't work, as the antenna would be shortened in a RF-way. But maybe the whole battery compartement is decoupled in a RF way from the rest of the PCB? Means the battery itself would then act as an antenna as well? Clever, if this is working like this. Any comments?

@JD8510: "How do you get to the bottom of the inner workings of a chip in order to discover these patents?"

Well, there are optical techniques to do so after you've striped away the housing with nitric acid. I even heard about tecniques, where layer by layer has been removed from such a chip to get to the inner workings. And if you've the money and therefore the material to do so, you're even able to read out single bits of memory cells. OTPs by optical ways, others by using a scanning electron microscope...

@ncb: IMHO there are no such small mono codecs on the market, as the additionally used space is much smaller than the advantace you're getting by adding a second channel. Most of the chip area is used by the core functionalities of the codec anyway.

Well, Li-Ion could also be used as a hyperonym of LiPo and Li-Ion. Means, a LiPo INDEED is one sort of Li-Ion based batteries...